Delta Time

Movement, animation speed, timers — almost everything that changes over time in a game needs to know how long the last frame actually took, since frame duration is never perfectly constant.

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Overview

DeltaTime exposes a singleton delta, contained in the header "remake2d/time.hpp". It tracks how long the previous frame took, and caps the frame rate to a configurable maximum.

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Methods

fmax tick(void)   const noexcept; // delta time of the current frame, in seconds
fmax FPS(void)    const noexcept; // current frames per second
fmax maxFPS(void) const noexcept; // current frame rate cap
void maxFPS(fmax) noexcept;       // set frame rate cap (clamped 30-1440)
void update(void);                // advance delta and dispatch signals

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Usage

Reading delta time

Multiplying a speed by tick is what keeps movement consistent regardless of how fast or slow a frame runs:

player.move({speed * (f32)rmk::delta.tick(), 0});

FPS is simply the inverse of tick, handy for an on-screen counter:

rmk::f32 fps = (rmk::f32)rmk::delta.FPS();

Capping the frame rate

By default the frame rate is capped at 120. maxFPS changes that limit, clamped between 30 and 1440:

rmk::delta.maxFPS(60.0);

Update

update measures the elapsed time since the last call, updates tick and FPS, and dispatches every bound Signal in the engine, including timers and events:

// In render loop
rmk::delta.update();

Info

Update is already called automatically by loop, so it never needs to be called manually unless a custom loop is being driven by hand.

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